Folks who love to complain about the price of coffee at Starbucks just got some coal for the fire: prices are going up.

The coffee giant on Friday announced that it's raising prices starting Tuesday on some -- but not all -- drinks by 5 cents to 20 cents. At the same time, the price of packaged coffee that it sells to grocery stores will increase by $1, from $8.99 to $9.99 for a 12 ounce bag.

Executives declined to specifically explain why they're raising prices right now -- even as coffee bean prices have rocketed in recent weeks "There are many factors that contribute to our pricing decisions, including competitive dynamics and our overall cost structure," spokesman Zack Hutson said in an emailed statement.

But commodity costs may not be the main driver. Historically coffee commodity costs have comprised 10% of Starbucks operating structure, Hutson says. "We have virtually all of our coffee needs covered for fiscal year 2014, and more than 40 percent of our coffee needs covered for fiscal year 2015."

The free college tuition program that Starbucks announced this week with Arizona State University's online program, he says, "is in no way related" to the price hikes.

The coffee price increases will boost the average ticket at Starbucks by less than 1%, says Hutson. "The vast majority of our customers will not be affected" by the price increase, he says. Fewer than 20% will be affected, he estimates.

The price hike comes about one year after the last national beverage price increase, which was June, 2013.

Meanwhile, it's the grocery store where consumers will feel the biggest hit. There, prices on its roast and ground packaged coffee products will jump a hefty 8% on July 21.

Hutson says Starbucks will be "effectively restoring prices" to their April 2013 levels -- after decreasing prices by 10% last April.

Not affected by the grocery store price boost: K-Cups, Via and Seattle's Best Coffees.

Others have raised coffee prices recently, too. Earlier this month, J.M. Smucker's announced that it was raising the price of Folgers bagged coffee by 9%.